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 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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package javax.xml.namespace;

import java.util.Iterator;

/**
 * <p>Interface for read only XML Namespace context processing.</p>
 *
 * <p>An XML Namespace has the properties:</p>
 * <ul>
 * <li>Namespace URI:
 * Namespace name expressed as a URI to which the prefix is bound</li>
 * <li>prefix: syntactically, this is the part of the attribute name
 * following the <code>XMLConstants.XMLNS_ATTRIBUTE</code>
 * ("xmlns") in the Namespace declaration</li>
 * </ul>
 * <p>example:
 * <code>&lt;element xmlns:prefix="http://Namespace-name-URI"&gt;</code></p>
 *
 * <p>All <code>get*(*)</code> methods operate in the current scope
 * for Namespace URI and prefix resolution.</p>
 *
 * <p>Note that a Namespace URI can be bound to
 * <strong>multiple</strong> prefixes in the current scope.  This can
 * occur when multiple <code>XMLConstants.XMLNS_ATTRIBUTE</code>
 * ("xmlns") Namespace declarations occur in the same Start-Tag and
 * refer to the same Namespace URI. e.g.<br />
 * <pre>
 * &lt;element xmlns:prefix1="http://Namespace-name-URI"
 *          xmlns:prefix2="http://Namespace-name-URI"&gt;
 * </pre>
 * This can also occur when the same Namespace URI is used in multiple
 * <code>XMLConstants.XMLNS_ATTRIBUTE</code> ("xmlns") Namespace
 * declarations in the logical parent element hierarchy.  e.g.<br />
 * <pre>
 * &lt;parent xmlns:prefix1="http://Namespace-name-URI">
 *   &lt;child xmlns:prefix2="http://Namespace-name-URI"&gt;
 *     ...
 *   &lt;/child&gt;
 * &lt;/parent&gt;
 * </pre></p>
 *
 * <p>A prefix can only be bound to a <strong>single</strong>
 * Namespace URI in the current scope.</p>
 *
 * @author <a href="mailto:Jeff.Suttor@Sun.com">Jeff Suttor</a>
 * @see javax.xml.XMLConstants javax.xml.XMLConstants for declarations of common XML values
 * @see <a href="http://www.w3.org/TR/xmlschema-2/#QName"> XML Schema Part2: Datatypes</a>
 * @see <a href="http://www.w3.org/TR/REC-xml-names/#ns-qualnames"> Namespaces in XML</a>
 * @see <a href="http://www.w3.org/XML/xml-names-19990114-errata"> Namespaces in XML Errata</a>
 * @since 1.5
 */

public interface NamespaceContext {

  /**
   * <p>Get Namespace URI bound to a prefix in the current scope.</p>
   *
   * <p>When requesting a Namespace URI by prefix, the following
   * table describes the returned Namespace URI value for all
   * possible prefix values:</p>
   *
   * <table border="2" rules="all" cellpadding="4">
   * <thead>
   * <tr>
   * <td align="center" colspan="2">
   * <code>getNamespaceURI(prefix)</code>
   * return value for specified prefixes
   * </td>
   * </tr>
   * <tr>
   * <td>prefix parameter</td>
   * <td>Namespace URI return value</td>
   * </tr>
   * </thead>
   * <tbody>
   * <tr>
   * <td><code>DEFAULT_NS_PREFIX</code> ("")</td>
   * <td>default Namespace URI in the current scope or
   * <code>{@link
   * javax.xml.XMLConstants#NULL_NS_URI XMLConstants.NULL_NS_URI("")}
   * </code>
   * when there is no default Namespace URI in the current scope</td>
   * </tr>
   * <tr>
   * <td>bound prefix</td>
   * <td>Namespace URI bound to prefix in current scope</td>
   * </tr>
   * <tr>
   * <td>unbound prefix</td>
   * <td>
   * <code>{@link
   * javax.xml.XMLConstants#NULL_NS_URI XMLConstants.NULL_NS_URI("")}
   * </code>
   * </td>
   * </tr>
   * <tr>
   * <td><code>XMLConstants.XML_NS_PREFIX</code> ("xml")</td>
   * <td><code>XMLConstants.XML_NS_URI</code>
   * ("http://www.w3.org/XML/1998/namespace")</td>
   * </tr>
   * <tr>
   * <td><code>XMLConstants.XMLNS_ATTRIBUTE</code> ("xmlns")</td>
   * <td><code>XMLConstants.XMLNS_ATTRIBUTE_NS_URI</code>
   * ("http://www.w3.org/2000/xmlns/")</td>
   * </tr>
   * <tr>
   * <td><code>null</code></td>
   * <td><code>IllegalArgumentException</code> is thrown</td>
   * </tr>
   * </tbody>
   * </table>
   *
   * @param prefix prefix to look up
   * @return Namespace URI bound to prefix in the current scope
   * @throws IllegalArgumentException When <code>prefix</code> is <code>null</code>
   */
  String getNamespaceURI(String prefix);

  /**
   * <p>Get prefix bound to Namespace URI in the current scope.</p>
   *
   * <p>To get all prefixes bound to a Namespace URI in the current
   * scope, use {@link #getPrefixes(String namespaceURI)}.</p>
   *
   * <p>When requesting a prefix by Namespace URI, the following
   * table describes the returned prefix value for all Namespace URI
   * values:</p>
   *
   * <table border="2" rules="all" cellpadding="4">
   * <thead>
   * <tr>
   * <th align="center" colspan="2">
   * <code>getPrefix(namespaceURI)</code> return value for
   * specified Namespace URIs
   * </th>
   * </tr>
   * <tr>
   * <th>Namespace URI parameter</th>
   * <th>prefix value returned</th>
   * </tr>
   * </thead>
   * <tbody>
   * <tr>
   * <td>&lt;default Namespace URI&gt;</td>
   * <td><code>XMLConstants.DEFAULT_NS_PREFIX</code> ("")
   * </td>
   * </tr>
   * <tr>
   * <td>bound Namespace URI</td>
   * <td>prefix bound to Namespace URI in the current scope,
   * if multiple prefixes are bound to the Namespace URI in
   * the current scope, a single arbitrary prefix, whose
   * choice is implementation dependent, is returned</td>
   * </tr>
   * <tr>
   * <td>unbound Namespace URI</td>
   * <td><code>null</code></td>
   * </tr>
   * <tr>
   * <td><code>XMLConstants.XML_NS_URI</code>
   * ("http://www.w3.org/XML/1998/namespace")</td>
   * <td><code>XMLConstants.XML_NS_PREFIX</code> ("xml")</td>
   * </tr>
   * <tr>
   * <td><code>XMLConstants.XMLNS_ATTRIBUTE_NS_URI</code>
   * ("http://www.w3.org/2000/xmlns/")</td>
   * <td><code>XMLConstants.XMLNS_ATTRIBUTE</code> ("xmlns")</td>
   * </tr>
   * <tr>
   * <td><code>null</code></td>
   * <td><code>IllegalArgumentException</code> is thrown</td>
   * </tr>
   * </tbody>
   * </table>
   *
   * @param namespaceURI URI of Namespace to lookup
   * @return prefix bound to Namespace URI in current context
   * @throws IllegalArgumentException When <code>namespaceURI</code> is <code>null</code>
   */
  String getPrefix(String namespaceURI);

  /**
   * <p>Get all prefixes bound to a Namespace URI in the current
   * scope.</p>
   *
   * <p>An Iterator over String elements is returned in an arbitrary,
   * <strong>implementation dependent</strong>, order.</p>
   *
   * <p><strong>The <code>Iterator</code> is
   * <em>not</em> modifiable.  e.g. the
   * <code>remove()</code> method will throw
   * <code>UnsupportedOperationException</code>.</strong></p>
   *
   * <p>When requesting prefixes by Namespace URI, the following
   * table describes the returned prefixes value for all Namespace
   * URI values:</p>
   *
   * <table border="2" rules="all" cellpadding="4">
   * <thead>
   * <tr>
   * <th align="center" colspan="2"><code>
   * getPrefixes(namespaceURI)</code> return value for
   * specified Namespace URIs</th>
   * </tr>
   * <tr>
   * <th>Namespace URI parameter</th>
   * <th>prefixes value returned</th>
   * </tr>
   * </thead>
   * <tbody>
   * <tr>
   * <td>bound Namespace URI,
   * including the &lt;default Namespace URI&gt;</td>
   * <td>
   * <code>Iterator</code> over prefixes bound to Namespace URI in
   * the current scope in an arbitrary,
   * <strong>implementation dependent</strong>,
   * order
   * </td>
   * </tr>
   * <tr>
   * <td>unbound Namespace URI</td>
   * <td>empty <code>Iterator</code></td>
   * </tr>
   * <tr>
   * <td><code>XMLConstants.XML_NS_URI</code>
   * ("http://www.w3.org/XML/1998/namespace")</td>
   * <td><code>Iterator</code> with one element set to
   * <code>XMLConstants.XML_NS_PREFIX</code> ("xml")</td>
   * </tr>
   * <tr>
   * <td><code>XMLConstants.XMLNS_ATTRIBUTE_NS_URI</code>
   * ("http://www.w3.org/2000/xmlns/")</td>
   * <td><code>Iterator</code> with one element set to
   * <code>XMLConstants.XMLNS_ATTRIBUTE</code> ("xmlns")</td>
   * </tr>
   * <tr>
   * <td><code>null</code></td>
   * <td><code>IllegalArgumentException</code> is thrown</td>
   * </tr>
   * </tbody>
   * </table>
   *
   * @param namespaceURI URI of Namespace to lookup
   * @return <code>Iterator</code> for all prefixes bound to the Namespace URI in the current scope
   * @throws IllegalArgumentException When <code>namespaceURI</code> is <code>null</code>
   */
  Iterator getPrefixes(String namespaceURI);
}
